BLOG: What are the key drivers for SDN?

Paul Hutchison |
Feb. 1, 2013

The question is not whether Software Defined Networking has any relevance for enterprise networking, but rather: what is the best way forward?

Plenty has already been written about the complexity, management and security problems caused by the transition from yesterday's closed, plug-in wired networks to today's permeable mobile networks linking a shifting population of wireless users with many of their own personal devices, otherwise known as the BYOD phenomenon.

There are also the growing pressures of virtualisation, growing reliance on video and other bandwidth-hungry applications, the problem of IPv6 readiness, emerging threats to data security and government legislation over privacy laws and border control of data.

Potential answers to these challenges are emerging from the development of Software Defined Networking (SDN) - achieved by replacing the brick-by-brick hardware management of a network with central software control system - is opening up a whole new world of opportunities for enterprise IT. With SDN's global visibility and policy control, administrators can dynamically provision services across the network to make it more elastic and optimise the use of resources.

Service-aware routing can streamline delivery of video and other lengthy traffic flows according to a user's profile, the congestion state of network, and other parameters. SDN creates an orchestrated tool kit of centralised applications that permit scalable, granular bandwidth allocation: you can use SDN to program the right access, security, QoS, and other policies along with the pipelines for each flow to offer high-level services, or an optimal user experience, without having to configure a whole lot of boxes along the path.

One of the biggest SDN deployments to date must be the Google WAN linking several large data centres across Europe, North America and the Asia Pacific. Commented Jim Wanderer, Google's Director of Engineering, Platforms Networking, when asked about its first two years of operation: "I can sum up that experience by saying OpenFlow SDN has worked really well for us, that Google couldn't have achieved the results it has without SDN."

The question is not whether SDN has any relevance for enterprise networking, but rather: what is the best way forward? Choose a company that supports an open standards-based approach rather than locking you into a proprietary straightjacket, and that currently means one that supports the OpenFlow standard promoted by the Open Networking Foundation (ONF).

The role of OpenFlow

OpenFlow is an industry-standard protocol that allows network operators to reprogram a network's control plane from a central interface. Whereas in a normal router or switch the fast packet forwarding (data plane) and the high-level routing decisions (control plane) happen in the same device, with OpenFlow, these two functions are separated: the data plane still resides on the switch, while the high-level routing decisions are moved to a separate controller. The open flow switch and controller communicate via the OpenFlow protocol.